Sintering ignition process.



C. W. ADAMS, JR. SINTERING IGNHION PROCESS.

APPLICATION FILED JAN.19. l9ll.

Patented Apr. 8, 1919. 2 SHEETSSHEETI A TTOR/VEYS C. W. ADAMS, JR. SINTERING IGNITION PROCESSL APPLICATION FILED IAN- I9, I9I7- 1,299,892, Patented Apr. 8,1919.

2 SHEETS-SHEET-Z- W/TNESS I I //VVE/VTO/? i CHARLES W. ADAMS, JR., OF MURRAY, UTAH, ASSIGNOR TO AMERICAN SMELTING & REFINING 00., A CORPORATION OF NEW JERSEY.

SINTElRING IGNITION PROCESS.

relates to an improvement in the steps incidental to, that part of the process whlch relates to 'the igniting of the charge of ore.

One method of sintering ores as at present practised is to deposit a layer of the ore on the upper run of an endless series of grates or pallets which carry the layer of ore under some form of igniting devlce and over one or more wind or suction boxes arranged to draw air downwardly through the igniting charge.

' of ore and the speed of the pallets across the wind boxes are so proportioned that the'ore is roasted and sintered by the time the ore has reached the end of its travel.

Numerous forms of igniting devices have heretofore been used. A small coal burning furnace has been used with some success but a furnace using some kind of hydrocarbon fluid such as gasolene, oil or gas has so far proved to be the most satisfactory. While these hydro-carbon furnaces are en-' tirely satisfactory in igniting certain classes of ores, when used with other classes of ores they are other reasons because the process as practised with these furnaces entail serious metal losses especially in the lead and silver metals.

Further it appears that when these hydrocarbon burning furnaces are used with certain ores the intense ignition incidental to a glazed or fused crust to the initial part of their use causes form on the ore during the sintering operation and this crust makes the charge semi-impervious to the passage of the air so that an amount of oxygen is the charge insufiicient to complete .the formation of the compounds containing S0 and S0 radicals. The result is that the sulfur in elemental form is carried into the fines and passageways. nder temperature conditions suitable there- 'Specification of Letters Patent.

. sintering,

The depth of the layer seriously objectionable, among Patented Apr. 8, 1919.

Application area January 19, 1917. Serial No. 143,236.

for, this elemental sulfur ignites, causing rapid expansion of the gases. A condition similar to an explosion takes place which interferes with the successful operation of the'process. 7

Accordingly, one of the objects of this invention is to improve particularly in the igniting features thereof, so that the metal losses may be reduced to a minimum, and, incidentally to this feature, to eliminate the serious danger from the igniting of elemental sulfur in the fines.

the usual method of A further object of the invention is to i provide a simple and inexpensive process by means of which the ore may be ignited economically and to provide a process susceptible of such control that the mass of igniting material fed per unit of ore mass may be varied readily to suit the requisites of the particular ore under treatment.

One method of obtaining these objects is to ignite been placed on the traveling pallets and to effect the ignition without the intensity of igniting action characterizing the active flame form of ignition heretofore used in operations of this character. With the present installation of one known form of sintering machine, this action is most satisfactorily effected by depositing a thin layer of a flameless body such as a hot roasted ore on the spread charge of ore to be roasted just before the charge with its hot top layer is passed over the vacuum boxes. A thin layer of hot sulfid ore oalcines having a 12 to 15 per cent. sulfur content has been used with much satisfaction in a plant where such an ore is available but it is to be understood that this particular ore is merely suggestive of one type of ore suitable for the purpose and practically any semiroasted ore or other hot product available abouta smelting plant may be utilized to effect the igniting feature of this invention.

As a matter of economy in handling and to maintain afairly high ignitin temperature, the hot ore is fed preferalfiy from a furnac arranged with its outlet close to the the charge of ore quietly after it has charge nozzle of of the burning zone travels slowly and quietly down through the ore thus com-. pletely sintering the charge.

The process has been carried out with advantage by means of a sintering machine of the conveyer type such as illustrated in the accompanying drawings in which Figure 1 is a side elevation of one end of a Dwight and Lloyd sintering machine shown in connection with an ore supplying furnace and Fig. 2 is a transverse sectional view taken on the line 22 of Fig. 1.

The machine illustrated is the charging end of a straight line sintering machine including a supporting frame 3 which sup ports an endless chain of grates or pallets 4 passing about and actuated by some suitable driving means such as a sprocket wheel 5. A feed hopper 6is positioned to direct a continuous stream of\the ore to be treated on to the upper run of ates and to spread the same evenly in a lay r of uniform thickness. The most satisfactory working thickness of this layer is dependent obviousl upon the capacity of the machine, the rate of travel of the grates and ore under treatment, but in general, working with a layer of fourto six inches has given the most satisfactory results.

he igniting device illustrated includes a small mechanical roasting furnace 7 having a discharge outlet 8 for the hot ore 9 and a depending hopper 10 leading down from the furnace outlet and terminating in a discharge nozzle 11 arranged to spread the hot ore from the furnace in a thin layer on top of the charge of ore to be roasted. The disthe hopper or chute 10 is in the form of an adjustable gate arranged to controlthe depth of layer of hot ore discharged from the chute on to the ore to be roasted. In the device illustrated this adj ustable nozzle is in the form of a long narrow band telescoping the lower end ofthe chute and adjustable in its vertical position by, means of the hand wheel 12 acting through the pinions 13 on a hand wheel shaft 14 meshing with racks 15 projecting upwardly from the nozzle. Positioned beyond the ore discharging chute is a ;":al1ty of vacuum or wind boxes 16 a which is shown in the drawings.

These wind boxes are designed to cause a downwardly directed draft of air to pass through the top hot layer of ore and through v the charge of ore'to be sintered as is usual with devices of this character.

In operation it will be understood that the charge of ore to be treated is spread evenly on the grates as is usual with machines of this character using other forms of igniting devices. A layer of hot ore from the roast ing furnace is then spread evenly on top of the spread charge to the character of the I sintered than by 1-. In the art part of one of be sintered, the v depth of the layer of hot ore best suited for a successful ignition depending upon the char- -tering Charge has eliminated several objectionable'features of the usual hydro-carbon flame method as heretofore used and has produced results and advantages which has improved the process from a commercial standpoint. The metal losses which have heretofore amounted to a considerablepercentage of the charge have been reduced materially so that these losses with the improved igniting are now almost negligible.

The sulfur present in the charge appears to be completely oxidized so that little, if any, elemental sulfur passes into the flues. This feature has resulted in a mateiial saving in cost of the flue construction in that the safety valves and other devices for preventing explosions in the flue can now be eliminated. This new method also eliminates the possibility of danger resulting from the handling of liquid fuel in the old form of ignlters and also eliminates the cost of this I liquid fuel w *ich recently has added materially to the cost of the sintering operation.

Further, this new process is valuable in. that -the finished product is more thoroughly the over ignition to which the charge has heretofore beensubjected and this perfected sintering is obtained at a ma-' terially less cost per ton of charge treated.

I claim:

, of sintering ores, the process which consists in spreading a uniformly thick layer. of red hot ore in direct physical contact with the top of a charge of the ore to be sintered and subjecting the layer and charge to the action of a downwardly directed current of air passed through the same.

2. In the art of sintering ores, the process which consists in subjecting the ore to be sintered to the action of a body of hot ore in contact therewith and passing a current of airthrough the ore to be sintered and in, a direction away from the body of hot ore.

3. In the art of sintering ores" containing sulfur, the process which consists in covering a charge sulfur to be sintered with a adapted to prevent the formation of a glazed or fused top crust to the charge during the sintering of the charge and sintering the ore so covered.

4. In the art of sintering ore containing sulfur, the process which consists in depositing on top of a layer of theore, a ley'er of Signed at Murray, in the colinty of Salt red hetore havir g a temperature sufficiently Lake, and State of Utah, thus 14th day of high to quietly ignite the charge'and at a-' December A. D. 1916.

temperature sufficiently low so as to ,distil CHARLESW. ADAMS, JR. 5 only a relatively'small amount of elemental Witnesses: t v

sulfur from the ol e and subjecting the ig- 'A. H. RICHARDS;

nited oreto a down draft of an.

W. W. NORTON. 

